Managing Database Resources - OCP: Oracle Database 12c Administrator Certified Professional - page 481

The query results show that you can transport the database on this server to any of those
platforms listed.
The remaining prerequisite steps are as follows:
1. Verify that there are no restrictions or limitations that the source or destination data-
base may encounter.
2. Verify that the destination and source systems have the same Oracle version, critical patch
updates, patch-set version, and patch-set exceptions. Verify using the OPatch utility.
3. Determine if you will use the source or destination system to perform the conversion.
Step 2: Identify All External Files and Directories
Verify that you have created all necessary directories on the destination system as well
as determined which external database files, such as BFILES and external tables, need to
migrate to the destination. Query DBA_DIRECTORIES to report file system locations. Execute
the supplied function DBMS_TDB.CHECK_EXTERNAL to identify external tables, directories,
and BFILES that you'll need to move as part of the migration. Here's an example:
SQL> set serveroutput on
SQL> declare
tdb_check boolean;
begin
tdb_check := dbms_tdb.check_external();
end;
/
The following external tables exist in the database:
SYS.OPATCH_XML_INV, SH.SALES_TRANSACTIONS_EXT
The following directories exist in the database:
SYS.ORACLE_HOME, SYS.ORACLE_BASE, SYS.OPATCH_LOG_DIR, SYS.OPATCH_SCRIPT_DIR,
SYS.XSDDIR, SYS.DATA_PUMP_DIR, SYS.ORACLE_OCM_CONFIG_DIR,
SYS.ORACLE_OCM_CONFIG_DIR2, SYS.ORACLECLRDIR, SYS.DATA_FILE_DIR, SYS.MEDIA_DIR
The following BFILEs exist in the database:
PM.PRINT_MEDIA]
PL/SQL procedure successfully completed.
SQL>
Once you start the migration, don't create any new external objects in the source
database.